Warming-up
Important
The aim of warming up is to increase the physical performance and avoid sport injuries.
Warming up should therefore be regular, disciplined and correct in accordance to the exercises presented.
Active warming up helps to prevent injuries; a warm up period is the first part of every training session or preparation for competition. The warm up starts slowly and gradually involves all muscles and body parts. In addition to preparing the athlete mentally, warming up also has several physiological benefits.
The importance of a warm up prior to exercise cannot be overstressed certainly for an intensive sport like judo. Warming up raises the body temperature and prepares the muscles, nervous system, tendons, ligaments, and the cardiovascular system for upcoming stretches and exercises. The chances of injury are greatly reduced by increasing muscle elasticity.
Put into practice
Tap games
Activities such as tap games involved with falling techniques or rolls (ukemi waza).
Tap games are fun and help building condition. A warm up period is the first part of every training session or preparation for competition. The warm up starts slowly and gradually involves all muscles and body parts. In addition to preparing the athlete mentally, warming up also has several physiological benefits.
The importance of a warm up prior to exercise cannot be overstressed. Tap games raises the body temperature and prepares the muscles, nervous system, tendons, ligaments, and the cardiovascular system for upcoming stretches and exercises. The chances of injury are greatly reduced by increasing muscle elasticity and involved with falling techniques it also helps stabilize confidence and overcomes fear of falling.

Copy cat: (stretching and power training)
Stand in a circle and everybody is copying the teacher and after that, the students.
Here can be trained in improving the necessary bodily skills like:
Flexibility, speed and mobility (stand, sit, lay on your belly, back, etc.)
Power: (push-ups, sit-ups)
Fall techniques (ukemi-waza) all in a playful way.
Preparation lesson ne-waza
Reminder of a previous lesson ne-waza, where you want to build up to the main chapter of your lesson:
Know what you thought the students and let them rehearse this in play form for 10 minutes.
After that, you make randori form of what has been thought.
For instance: if you trained a hold down, than this is the starting position for the randori-waza.
Randori-ne-waza (playful competition on the ground)

Advantage and disadvantage
The number of physiological processes improve by higher body temperature
Owing to the widening of the blood vessels, the bloodstream to the muscles becomes higher. (Vasodilatation) Therefore the muscle gets more oxygen so that the aërobe energy source optimises and there are fewer waste products. (lactic acid)
The muscles warm up and are prepared for the work, which they have to deliver during the training and the match. The metabolisms are activated and therefore the muscle energy is available. There is an increase of the sensitivity of the nerve receptors and a rising of the nerveconductorspeed.
Other parts of the body that profit of the increased temperature: the heart (the beats per minute must increase and per beat there is more blood circulated) and the lungs (which are ventilated better, thanks to the blood stream it is able to access more oxygen).
A good warming up is not only a positive influence to the strength but also to the speed, the suppleness and the endurance.

Summary warming Up:
1 - Raises body temperature
2 -Increases metabolic rate
3 -Increases heart and respiratory rate
4 -Prepares the muscles and nervous system for exercise
Remarks:
Time (approximately 20 minutes) and intensity (one has to start perspiring) should be individually adjusted, as well as to the level of the athlete as to the environmental circumstances.
Mostly the worming up takes place in groups but certain judoka’s need more warming up than others.
A solid warming up for a well-trained athlete is for an untrained individual an exhausting exertion.
Above all one should realise that one should take in account the judoka’s bodily restriction.
Note:
Beware that a judoka with the Down syndrome by which one of the physical characterises can be muscular weakness (hypotonie) requires a totally different warming up than a judoka with Cerebral Paralyse (hypertonie).